A passive optical network (PON) is a system for providing network access over “the last mile.” The PON is a point to multi-point network comprised of an optical line terminal (OLT) at the central office, an optical distribution network (ODN), and a plurality of optical network units (ONUs) at the customer premises. Typically, downstream data transmissions are broadcast to all of the ONUs, while upstream data transmissions are transmitted to the OLT using time division multiple access (TDMA) or wave division multiple access (WDMA). PON systems, such as Gigabit PONs (GPONs), may support some security features to protect user data, e.g., for the downstream broadcast. For example, the broadcast transmissions from the OLT to the ONU may be encrypted.